OpenCV与Socket实现树莓派获取摄像头视频至电脑

OpenCV能够为我们带来便捷的图像处理接口，但是其处理速度在一块树莓派上肯定是不尽如人意的。尤其当我们想要使用复杂的算法时，只能把算法托到服务器上才有可能。这里介绍了一种方法，实现树莓派传输Mat至电脑。

准备工作

1、配置好树莓派上的OpenCV.
2、配置好电脑上的OpenCV.

思路

Socket实现方法较为简单，但在此处需要注意的是：
树莓派上的，是linux系统；而我电脑上是windows系统，需要注意这一点来进行编程。

代码

树莓派作为客户端，发送Mat.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 
#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main()
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    portno = atoi("8888");
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");
    server = gethostbyname("10.138.216.104");//这里填IP地址
    if (server == NULL) {
        fprintf(stderr, "ERROR, no such host
");
        exit(0);
    }
    bzero((char *)&serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr,
        (char *)&serv_addr.sin_addr.s_addr,
        server->h_length);
    serv_addr.sin_port = htons(portno);
    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
        error("ERROR connecting");

    VideoCapture cap(0);
    Mat frame;
    while (true)
    {
        cap >> frame;
        cvtColor(frame, frame, CV_BGR2GRAY);
        // Send data here
        int bytes = send(sockfd, frame.data, frame.total()*frame.elemSize(), 0));
    }
    waitKey(0);
    return 0;
}

服务器接收并显示

    #include <winsock2.h>  
    #include <opencv.hpp>
    using namespace cv;
    using namespace std;
    #pragma comment(lib,"ws2_32.lib")  
    #define imgSize 307200 //这里需要算一下，因为Visual Studio不能支持用变量初始化数组
    //imgSize=frame.total()*frame.elemSize();
    //即：如果为灰度图：图像的宽*图像的高 这里是640*480

    int main(int argc, char* argv[])
    {
    //初始化WSA  
    WORD sockVersion = MAKEWORD(2, 2);
    WSADATA wsaData;
    if (WSAStartup(sockVersion, &wsaData) != 0)
    {
        return 0;
    }
    //创建套接字  
    SOCKET slisten = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (slisten == INVALID_SOCKET)
    {
        printf("socket error !");
        return 0;
    }
    //绑定IP和端口  
    sockaddr_in sin;
    sin.sin_family = AF_INET;
    sin.sin_port = htons(8888);
    sin.sin_addr.S_un.S_addr = INADDR_ANY;
    if (bind(slisten, (LPSOCKADDR)&sin, sizeof(sin)) == SOCKET_ERROR)
    {
        printf("bind error !");
    }

    //开始监听  
    if (listen(slisten, 5) == SOCKET_ERROR)
    {
        printf("listen error !");
        return 0;
    }

    SOCKET sClient;
    sockaddr_in remoteAddr;
    int nAddrlen = sizeof(remoteAddr);

    cout << "Wait.." << endl;
    do
    {
        sClient = accept(slisten, (SOCKADDR *)&remoteAddr, &nAddrlen);
    } while (sClient == INVALID_SOCKET);
    cout<<"Received Information come from"<< inet_ntoa(remoteAddr.sin_addr)<<endl;

    int bytes = 0;
    while (1)
    {
        char socketData[imgSize];

        for (int i = 0; i < imgSize; i += bytes) {
            if ((bytes = recv(sClient, socketData + i, imgSize - i, 0)) == -1)
            {
                cout << "!Fault" << endl;
                exit(-1);
            }
        }

        // change the last loop to below statement
        Mat img(Size(640, 480), CV_8UC1, socketData);//根据摄像头大小自行修改
        imshow("Face_Socket", img);
        waitKey(1);
    }
    closesocket(slisten);
    WSACleanup();
    return 0;
}

先运行服务器，后运行客户端（其实无所谓），我们就可以在服务器上看到树莓派通过摄像头获取到的帧，那么就可以对齐进行很多操作了。